This invention relates to apparatus for harvesting berries on low plants, and in particulars, is directed to apparatus for harvesting wild blueberries in commercial quantities.
The market, demand for wild blueberries is such that over the last several years, blueberry fields have increased in number and in size wherever the climate and soil conditions are appropriate for growth thereof.
Harvesting of wild blueberries is usually done from mid-July to early August, depending upon the location of the field and the weather conditions at that time. Hence, it is a common practice for a blueberry grower to harvest fields ranging from 25 acres to 250 acres within a 2-3 weeks period.
The task is too tedious to be done manually, or to be done by workers using manual rakes and implements, Therefore, there is a significant demand for self-propelled mechanical harvesters.
A number of self-propelled apparatus for harvesting blueberries is available commercially. One type of machine is described in Canadian patent no. 523,354 to L. C. Getsinger, April 1956. The machine has a drum, and a number of combs spaced at regular angular intervals, and across the surface of this drum. The drum rotates against the direction of the travel of the machine such that the fingers of the combs intersect with berry plants and rake the fruits thereon.
The combs are arranged to follow a cam groove so that the fingers withdraw within the surface of the drum at pre-determined location on the circumference of their course to facilitate the release of fruits onto a slide and into an exit conveyor.
Other similar self-propelled machines using articulated fingers, with an exit conveyor placed at the centre of the drum, are described in:
Canadian Patent: 948,858 to G. L. Gray, June 1974 PA1 Canadian Patent.: 961,275 to C. G. Burton, Jan. 1975 PA1 and U.S. Pat. No. 3,675,406 to Grant et al, July 1972.
The articulation of fingers, the need for an exit conveyor, and the coordination of the various components require complex mechanics. The price of these machines is therefore relatively high, as well is the cost of maintenance thereof.
Another type of machine available commercially mounts on a farm tractor. The machine is described in Canadian patents no, 1,249,727 and 1,318,135, both to D. R. Bragg, and are dated in February 1989 and May 1993 respectively. The machine is also mechanically intricate, having similar articulated fingers and an exit conveyor as already described.
The mounting of the machine on a farm tractor requires intensive modifications to the tractor and the fitting of special fixtures. This installation is better done by specialized shop or by the harvester's manufacturer himself.
The high purchase value of this machine together with the substantial installation costs and the nature of the involvement for one needing his tractor for other work during the harvest period are amongst the factors disfavouring an acquisition of the machine by the small and medium size growers.
The invention cited above is probably the fastest machine available at this time, with a disclosed speed of 2 miles per hour. Conversely, excessive speed is known to clog the fingers of the combs with leaves, twigs and squashed berries. Thus, a cylindrical brush is installed adjacent to the drum, to clean the fingers before each sweep, thereby adding complexity to the machine. Nevertheless, the gatherings of this machine are known to contain much leaves and debris.